不同时间尺度下中国东部夏季最高温度观测与再分析资料的比较

Comparison of Reanalysis Data and Observations about Summer Maximum Temperature on Different Time Scales in Eastern China

利用中国气象局中国气象数据网提供的地面观测资料集及JRA-55、ERA-Interim、NCEP/NCAR和NCEP/DOE四种再分析资料集的日最高温度资料,运用线性分析、方差分析、EOF分析和滤波等方法,对1979—2013年中国东部地区夏季不同再分析资料和观测资料日最高温度的多时间尺度特征进行对比分析。结果表明:夏季最高温度多年平均由南向北逐渐降低,长江以南在30℃以上,JRA-55对东部地区夏季日最高温度的多年平均特征的再现能力较优;近35年东部地区夏季日最高温度整体呈增长趋势,长江中下游以及内蒙古东部地区增长趋势明显;再分析资料对最高温度长期变化特征的再现能力在不同地区各有优劣,JRA-55略优于其他资料。夏季最高温度空间上以长江中下游以南与其以北地区反位相变化为其主要特征,其中ERA-Interim的空间分布特征与观测资料较为相似,其次为NCEP/DOE;时间变化则以年际变化为主,ERA-Interim的年际变化特征最接近观测资料。JRA-55、NCEP/NCAR以及NCEP/DOE在21世纪之后变化特征与观测资料较为相似,表现为振幅减弱而后回升的趋势;在季节内尺度上,夏季日最高温度主要周期为20~60天,其方差贡献在云贵、东北地区以及甘肃东部、陕西一带较大,再分析资料对季节内时间尺度的再现能力由高到低依次为JRA-55、ERA-Interim、NCEP/DOE、NCEP/NCAR。

Based on daily maximum temperature derived from the ground observation dataset of China meteorological data sharing network（ OT） and JRA-55,ERA-Interim,NCEP/NCAR,NCEP/DOE reanalysis datasets,respectively,linear trend analysis,variance analysis,EOF analysis and filtering methods were used to compare multi-scale features of reanalysis and observation daily maximum temperature in summer during 1979—2013 in eastern China. Results showthat： The average daily maximum temperature in summer during 1979—2013 decreased gradually from south to north and is above 30 ℃ to the south of the middle and lower reaches of the Yangtze River; The ability of reanalysis data to depict these characteristics from high to lowis JRA-55,ERA-Interim,NCEP/DOE,NCEP/NCAR. In recent 35 years,the daily maximum temperature in summertime in the eastern region shows increasing trend,while the middle and lower reaches of the Yangtze river and eastern Inner Mongolia region shows obvious increase trend; The ability of reanalysis data to reproduce the characteristics in different regions have their own advantages and disadvantages,with JRA-55 slightly better than other datasets.The average daily maximum temperature in summer shows opposite distribution to the north and south of the middle and lower reaches of the Yangtze River,the distribution of ERA-Interim is very closely to the observations,then the NCEP/DOE. The temporal feature of summer maximum temperature is interannual variation,the ERA-Interim data is the one which interannual feature is most similar to the observations＇. After 21 st century,the temporal characteristics of JRA-55,NCEP/NCAR and NCEP/DOE is relatively similar to the observation data,showing the amplitude decreased and then picks up; The daily maximum temperature of summer main period is20 ~ 60 days. The variance contribution of intra seasonal variability of the summer daily maximum temperature in Yunnan,Guizhou,Northeast China and the eastern Gansu,Shanxi area is larger. The reproduction ability of the4 reanalysis for intra-seasonal variability from high to lowis JRA-55,ERA-Interim,NCEP/DOE and NCEP/NCAR.